An image sensor is a device that converts optical information into electrical information. At present, the image sensor mainly includes a charge coupled device (CCD) image sensor and a complementary metal-oxide semiconductor (CMOS) image sensor. Compared to the CCD image sensor, the CMOS image sensor (CIS) has wider applications. A CMOS image sensor circuit includes photosensitive components, transistors, capacitors and other structures.
However, the electrical performance of the conventional capacitor is poor and needs to be improved. The disclosed devices, circuits, and methods are directed to solve one or more problems set forth above and other problems in the art.